Study of barrier inhomogeneities using I-V-T characteristics of Mo/4H Schottky diode

In the present work we investigate the forward current voltage (I-V) characteristics, over a wide temperature range 298-498 K, of Mo/4H-SiC Schottky diode for which aluminum ion implantation was used to create the high resistivity layer forming the guard ring. The (I-V) analysis based on Thermionic Emission (TE) theory shows a decrease of the barrier height phi(B) and an increase of the ideality factor n when the temperature decreases. These anomalies are mainly due to the barrier height inhomogeneities at the metal/semiconductor interlace as we get a Gaussian distribution of the barrier heights when we plot the apparent barrier height phi(ap) versus q/2kT. The mean barrier height and the standard deviation obtained values are (phi) over bar (B0) = 1.160 eV and (sigma(0) = 88.049 mV, respectively. However, by means of the modified Richardson plot Ln(I-s/T-2)-(q(2)/sigma(2)(0)/2k(2)T(2) versus q/kT, the mean barrier height and the Richardson constant values obtained are (phi) over bar (B0) = 1.139 eV and A* =129.425 A/cm(2) K-2, respectively. The latter value of (phi) over bar (B0) matches very well with the mean barrier height obtained from the plot of phi(ap) versus q/2kT. The Richardson constant is much closer to the theoretical value of 146 A/cm(2) K-2. The series resistance R-s is also estimated from the forward current-voltage characteristics of Mo/4H-SiC Schottky contact. This parameter shows strong temperature dependence. The T-0 effect is validated for the 298-498 K temperature range for the used Schottky diode and provides a clear evidence for the barrier inhomogeneity at the Mo/4H-SiC interface. Finally, we note the impact of the implantation process as well as the choice of the used ion on the characterized parameters of the Schottky contact. (C) 2014 Elsevier B.V. All rights reserved.